Navien Error Code E205: Water Flow Sensor Failure
Warning: Your Navien boiler has detected a water flow sensor failure, which could lead to system damage if not addressed.
How to Fix Navien Code E205
- Check if your boiler is making any unusual noises, which could indicate air in the system.
- Try bleeding the air from the system using the built-in air vent.
- If the issue persists, do not attempt to fix it yourself. Contact a professional HVAC technician.
How to Reset Navien Code E205
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E205 Mean?
The E205 error on your Navien boiler indicates a malfunction in the water flow sensor. This sensor is responsible for monitoring the water flow rate through your boiler. If it's not working correctly, your boiler may not heat water efficiently, leading to system issues. The most common causes for this error are a faulty sensor or air in the system.
Common Causes
- Faulty water flow sensor
- Air in the system
- Incorrect water flow rate
- Clogged or dirty sensor
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Boiler is not heating water | Measure the water flow rate using a flow meter | Flow rate within the manufacturer's specified range |
| Air vent is open | Listen for air escaping while bleeding the system | Air escaping indicates a successful bleed |
Applicable Navien Models
Source Documentation
Referenced in 6 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Heating Supply Temp.Sensor | Check flow, thermistor connector. |
| Navien NCB-H Installation & Operation Manual | 129 | Heating Supply Temp.Sensor | Contact technical support at 1-800-519-8794. |
| Navien NFB-H Installation & Operation Manual | 116 | Heating Supply Temp.Sensor | Check flow, thermistor connector. |
| Navien NFC-H Installation & Operation Manual | 127 | Abnormal operation: heating supply thermistor | Auto RESET |
| Navien NHB-H Installation & Operation Manual | 119 | Heating Supply Temp.Sensor | Check flow, thermistor connector. |
| Navien NPF Installation & Operation Manual | 126 | Abnormal supply water-temp sensor operation for lower limit | This error occurs when the water temperature for supply or return does not operate properly. ● Turn off the furnace, turn it on again and check if the furnace operates properly. ● If the furnace is continuously inoperable, contact Technical Support at 1-800-519-8794. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Water Flow Sensor | 360-00010-00 | — | Find Part |
Related Codes on Same Models
Other codes that affect the same Navien model families as E205.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |